The Sunless Citadel was fairly easy to convert, at least for me. I changed it a bit though. I had it take place in Karnath under Fort Deepdark. In fact, the fort fell into Khyber and the surrounding villages were beset by the various kinds of blights, some dragged down into the depths to feed the Gulthias tree. I also changed the tree. In my version, during the Daelkyr incursion a hobgoblin war chief managed to plunged this specially crafted spear into a Daelkyr. The hobgoblin died in the process, and the shaft of the spear formed into the tree. For my players, destroying the tree freed the Daelkyr. Everyone the players encountered were either survivors, those changed by the tree, or the Dhakaani goblins looking to retrieve the spear as an artifact the secure their tribe as the next to lead after Haruuc eventually does or is killed.

I had someone suggest using Penumbra: Crime & Punishment, which was written by Keith Baker. Have a look at the topic I created for it, to see what people said about the book. (Feel free to bump the topic if you have any questions that didn't already get asked/answered.)

The Savage Tide Adventure Path (written for D&D 3.5) would do well in Eberron. You could either adapt the Isle of Dread as an island off the coast of Xen'Drik, or just rip apart the elements of it for inclusion of it deep in the Xen'Drik jungles; with the latter you could even include the island in an inland body of water big enough to house it. The beauty of Xen'Drik is that only the coasts are mapped, so the GM is free to do whatever they want with the rest of the continent.

You also might want to look into Hollow Earth Expedition for more material for Xen'Drik. You could use the HEE setting in all or some of the following ways; a waypoint in Xen'Drik that leads to a Hollow Eberron where the HEE setting is used in its entirety, adapt parts of the HEE setting to fleshing out Xen'Drik and/or use the HEE setting as a jumping point to another world in Eberronspace (using this you could use the idea of the invisible moon becoming visible in conjunction with making a inter-planetary gate flare open when it briefly becomes visible, allowing those that traverse through it to another planet or perhaps Hollow Eberron).

Angel Tarragon wrote:The Savage Tide Adventure Path (written for D&D 3.5) would do well in Eberron. You could either adapt the Isle of Dread as an island off the coast of Xen'Drik, or just rip apart the elements of it for inclusion of it deep in the Xen'Drik jungles; with the latter you could even include the island in an inland body of water big enough to house it. The beauty of Xen'Drik is that only the coasts are mapped, so the GM is free to do whatever they want with the rest of the continent.

IIRC Hellcow did a conversion that set it to the southeast of the Lhazaar Principalities. I think you can still find the conversion documents on the Paizo website.

It's not really a conversion anyway. Just a page and a half on how to integrate the STAP with Eberron, I was hoping for something far more useful; like how to substitute rather than just plopping everything from the modules, modified stat blocks for encounters better suited to play up the Eberron feel and other tidbits for each module for further customization rather than straight-up shoehorning.

In the link I provided above there was that, and three other articles giving details for adapting the next three modules in the series in more detail. Two of them should have been visible as soon as you opened the page, assuming you aren't looking at it on your phone.

Tyranny of Dragons for 5E for me is not a Forgotten Realms adventure. But, if you substitute Khyber for Hell, it's almost an exact match for ideas relating to Tiamat presented in 3.5E's Dragons of Eberron.

In other words, it would suit Eberron a lot better than FR except for the conversion work that would be required.

I placed Forge of Fury in the Seawall Mountains in Darguun, and I remember talking to someone in the old WotC forums who did the same thing. In my case I made it a Dhakaani ruin: its amazingly easy to reflavour Dwarven names to goblinoid simply by adding a vowel here and there, and both ordinary dwarves and Eberron hobgoblins tend to be stoic underground races interested in the crafts of war.

It was on the other side of The Deep Mine. I had Khundrukar be a lost Dwarf outpost that was re-purposed by the Dhakaani during the Daelkyr Wars. There was a whole plot about Dyrrn the Corruptor and breed leeches and aberrations. I actually had to alter a fair number of things. The orcs in the adventure became goblinoids that had gone insane from long-term Daelkyr exposure. The duergar in the adventure I had be part of the lost Clan Noldrun, some of whom found their way through Khyber to the old dwarf mine and were trying to make it their home. I'm pretty sure I excised the Troglodytes entirely. Nightscale, at the end, is a partially warped and aberrant dragon that was twisted in the womb by a breed leech and is as crazy as the cult.

Yeah, I decided the duergar were from Sarlona and had been brought there as part of a quori plot. I also added a couple of inspired/chosen, which tipped the encounters into unwinnable until they recruited the dragon, who didn't take kindly to the quori presence in her dungeon, or to the upheaval their plot was going to cause.

That adjustment, made merely to justify the presence of duergar, ended up dominating the campaign.

Sleeper in the Tomb of Dreams. Available to download from Wizards site, it was a Dungeon adventure originally: www.wizards.com/files/155_Sleeper.pdf
It's an interesting, trap-filled dungeon crawl with some light horror-themes. Originally set in the Nentir Vale world, but I converted it to Eberron with some flavour changes:

The Cult of the Raven Queen -> the Inspired
The relic, bones of Sir Malagant -> bones of a long-dead Psychic Warrior of the Inspired
Warwood - the King's Forest east of Sharn
Location of the hill and underground 'Tomb of the Sleeper' - near the City of Dead on the edge of Sharn

I made some hooks and other details specific to my Eberron 3.5 campaign, but otherwise took the adventure as written.